The answer depends on the model, some use 1gb accessable micro sd memory chips (Scorpion, Open Country Caller).
Yes you can program more than the listed number of calls on the unit. BUT, you cannot access them with the remote. e.g. A FX3's TX5 remote will not command more then 32 calls and a TX200 will not control more than 200 calls.. No real reason to program more on the unit when the unit's remote will not access them.
Hope that helps,
Justin
AllPredatorCalls.com